Appendices
The following main changes have been made within the appendices
Appendix 1 British Standards to which reference is made in the Regulations includes minor changes, and additions.
Appendix 3 Time/current characteristics of overcurrent protective devices and RCDs
The previous contents of Appendix 14 concerning earth fault loop impedance have been moved into
Appendix 3.
Appendix 6 Model forms for certification and reporting
This appendix includes minor changes to the certificates, changes to the inspections (for new installation work only) for domestic and similar premises with up to 100 A supply, and examples of items requiring inspection for an electrical installation condition report.
Appendix 7 (informative) Harmonized cable core colours
This appendix includes only minor changes.
Appendix 8 Current-carrying capacity and voltage drop
This appendix includes changes regarding rating factors for current-carrying capacity.
Appendix 14 Determination of prospective fault current
The contents of Appendix 14 concerning earth fault loop impedance have been moved into
Appendix 3. Appendix 14 now contains information on determination of prospective fault current.
Appendix 17 Energy efficiency
This is a new appendix that provides recommendations for the design and erection of electrical installations including installations having local production and storage of energy for optimizing the overall efficient use of electricity.
The recommendations within the scope of this appendix apply for new electrical installations and modification of existing electrical installations. Much of this appendix will not apply to domestic and similar installations.
It is intended that this appendix is read in conjunction with BS IEC 60364-8-1, when published in 2018
18th Edition IET Wiring Regulations – Guidance Note Books
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On-Site Guide (BS 7671:2018+A2:2022) (Electrical Regulations) – This publication has been further updated to include two subsequent amendments to the IET Wiring Regulations as BS 7671:2018+A2:2022